The present invention relates generally to the field of measuring and testing, and more specifically, to a three-dimensional semiconductor doping profiler. A restricted illumination source, such as a near-field scanning optical microscope, directs light at a small region of an electrically biased semiconductor surface. The bias on the semiconductor creates a space-charge region in the body of the semiconductor to a depth controlled by an external applied bias, and electrical current changes in the semiconductor are recorded during scanning at each bias level to provide a series of data related to local internal doping profiles. Scanning the illumination source laterally with respect to the semiconductor surface can then be used to generate a three dimensional doping profile.